In telecommunications systems having a message transmission route between a message source and a message sink, transmitting and receiving devices are used for message processing and transmission, in which
1) the message processing and message transmission can be carried out in a preferred transmission direction (simplex operation) or in both transmission directions (duplex operation), PA0 2) the message processing is analogue or digital, PA0 3) the message transmission is wire-based over the trunk transmission, or is carried out wire-free on the basis of various message transmission methods FDMA (Frequency Division Multiple Access), (Time Division Multiple Access) and/or CDMA (Code Division Multiple Access)--for example in accordance with radio standards such as DECT, GSM, WACS or PACS, IS-54, PHS, PDC etc. (cf. IEEE Communications Magazine, January 1995, pages 50 to 57; D. D. Falconer et al: "Time Division Multiple Access Methods for Wireless Personal Communications"). PA0 (1) in the form of an image, PA0 (2) as the spoken word, PA0 (3) as the written word, PA0 (4) as an encrypted word or image. PA0 a) simulation of the ISDN channel structure (D channel and 2 B channels), the D channel in particular in the following text, PA0 b) good bandwidth economy; particularly important for ISDN since some services already require two DECT channels for the B channel data rate of 64 kbps, PA0 c) minimum technical complexity. PA0 Common signalling channel on the C plane for all Terminal Endpoints TE connected to the ISDN connection. PA0 The TE-specific signalling channels to the network are separated therein by TE-specific addresses TEI (Terminal Endpoint Identifier). The access mechanism to the D channel ensures the sequence of the messages on a TE-specific basis. PA0 Throughput rate: 16 kbps PA0 Utilization: dependent on a large number of criteria, as a rule lower than the maximum capacity; jam situations possible, although these can be cleared quickly because of the high capacity. PA0 Use of TDMA time slots. PA0 In principle one C.sub.s channel (s=slow) is used per time slot for signalling (C plane in the DECT standard), and one associated channel (U plane in the DECT standard) for the user or useful information (throughput: 32 kbps). PA0 Throughput of the C.sub.s channel: 2 kbps. PA0 The C.sub.f channel occupies one time slot. PA0 Throughput of the C.sub.f channel: 25.6 kbps.
"Message" is a generic term which covers both the useful content (information) and the physical representation (signal). Despite a message having the same useful content--that is to say the same information--different signal forms may occur. Thus, for example, a message relating to a circuit may be transmitted
The type of transmission in accordance with (1) . . . (3) is in this case normally characterized by continuous (analogue) signals while, in the case of the transmission type according to (4), the signals are normally discontinuous (for example pulses, digital signals).
On the basis of this general definition of a message system, the invention relates to a method for controlling the setting up of transmission paths (bearers) in wire-free telecommunications systems, in particular in a DECT-specific RLL/WLL system (Radio Local Loop/Wireless Local Loop) which is included as a local message transmission loop in an ISDN system.
Using as references the documents "Nachrichtentechnik Elektronik (Telecommunications electronics), Berlin 45 (1995) Issue 1, pages 21 to 23 and Issue 3 pages 29 and 30" as well as IEE Colloguium 1993, 173; (1993), pages 29/1-29/7; W. Hing, F. Halsall: "Cordless access to the ISDN basic rate service", and on the basis of a DECT/ISDN Intermediate System DIIS according to ETSI Publication prETS 300xxx, Version 1.10, September 1996, FIG. 1 shows an "ISDN.revreaction.DECT-specific RLL/WLL" Telecommunications system IDRW-TS with an ISDN telecommunications subsystem I-TTS (cf. document "Nachrichtentechnik Elektronik (Telecommunications electronics ), Berlin 41-43, Parts: 1 to 10, Part 1: (1991) Issue 3, pages 99 to 102; Part 2: (1991) Issue 4, pages 138 to 143; Part 3: (1991) Issue 5, pages 179 to 182 and Issue 6, pages 219 to 220; Part 4 (1991) Issue 6, pages 220 to 222 and (1992) Issue 1, pages 19 to 20; Part 5: (1992) Issue 2, pages 59 to 62 and (1992) Issue 3, pages 99 to 102; Part 6: (1992) Issue 4, pages 150 to 153; Part 7: (1992) Issue 6, pages 238 to 241; Part 8: (1993) Issue 1, pages 29 to 33; Part 9: (1993) Issue 2, pages 95 to 97 and (1993) Issue 3, pages 129 to 135; Part 10: (1993) Issue 4, pages 187 to 190;") and a DECT-specific RLL/WLL telecommunications subsystem RW-TTS.
The DECT/ISDN Intermediate System DIIS and the RLL/WLL telecommunications subsystem RW-TTS are in this case preferably based on a DECT/GAP-System DGS (Digital Enhanced (previously: European) Cordless Telecommunication; cf. (1): Nachrichtentechnik Elektronik 42 (1992) January/February No. 1, Berlin, DE; U. Pilger "Struktur des DECT-Standards" (Structure of the DECT standard), pages 23 to 29 in conjunction with the ETSI publication ETS 300175-1 . . . 9, October 1992; (2): Telecom Report 16 (1993), No. 1, J. H. Koch: "Digitaler Komfort fur schnurlose Telekommunikation--DECT-Standard eroffnet neue Nutzungsgebiete" (Digital convenience for wire-free telecommunication--DECT standard opens up new fields of application), pages 26 and 27; (3): tec 2/93--Das technische Magazin von Ascom "Wege zur universellen mobilen Telekommunikation" (The technical magazine from Ascom "Means for universal mobile telecommunication"), pages 35 to 42; (4) Philips Telecommunication Review Vol. 49, No. 3, September 1991, R. J. Mulder: "DECT, a universal cordless access system"; (5): WO 93/21719 (FIGS. 1 to 3 with associated description)). The GAP standard (Generic Access Profile) is a subset of the DECT standard which has the task of ensuring interoperability of the DECT radio interface for telephone applications (cf. ETSI publication prETS 300444, April 1995).
The DECT/ISDN Intermediate System DIIS and the RLL/WLL telecommunications subsystem RW-TTS can alternatively be based on a GSM system (Groupe Speciale Mobile or Global System for Mobile Communication; cf. Informatik Spektrum 14 (1991) June, No. 3, Berlin, DE; A. Mann: "Der GSM-Standard--Grundlage fur digitale europaische Mobilfunknetze (The GSM standard--Basis for digital European mobile radio networks)", pages 137 to 152). Instead of this, it is also possible in the context of a hybrid telecommunications system for the ISDN telecommunications subsystem I-TTS to be designed as a GSM system.
Furthermore, other possible ways for producing the DECT/ISDN intermediate system DIIS, the RLL/WLL telecommunications subsystem RW-TTS or the ISDN telecommunications subsystems I-TTS include the systems mentioned initially as well as future systems which are based on the known multiple access methods FDMA, TDMA, CDMA (Frequency Division Multiple Access, Time Division Multiple Access, Code Division Multiple Access) and hybrid multiple access methods formed from them.
The use of radio channels (for example DECT channels) in classical cable-based telecommunications systems, such as ISDN, is becoming increasingly important, particularly against the background of future alternative network operators without their own complete cable network.
Thus, for example in the case of the RLL/WLL telecommunications subsystem RW-TTS, the wire-free connection technology RLL/WLL (Radio in the Local Loop/Wireless in the Local Loop) for example including the DECT system DS, ISDN services can be made available to the ISDN subscriber on standard ISDN interfaces (cf. FIG. 1).
In the "ISDN.revreaction.DECT specific RLL/WLL" telecommunications system IDRW-TS according to FIG. 1, a telecommunications subscriber (user) TCU (Tele-Communication User) with TE (Terminal Endpoint; Terminal Equipment), is included in the ISDN world, with the services available in it, for example via a standardized S interface (S-BUS), the DECT/ISDN Intermediate System DIIS, which is designed as a local message transmission loop--is preferably DECT-specific and is contained in the RLL/WLL telecommunications subsystem RW-TTS--(first telecommunications subsystem), a further standardized S interface (S-BUS), a Network Termination NT and a standardized U interface of the ISDN telecommunications subsystem I-TTS (second telecommunications subsystem).
The first telecommunications subsystem DIIS essentially comprises two telecommunications interfaces, a first telecommunications interface DIFS (DECT Intermediate Fixed System) and a second telecommunications interface DIPS (DECT Intermediate Portable System), which are connected to one another without wires, for example via a DECT radio interface. Because of the quasiposition-based first telecommunications interface DIFS, the first telecommunications subsystem DIFS forms the local message transmission loop defined above in this context. The first telecommunications interface DIFS contains a Radio Fixed Part RFP, an InterWorking Unit IWU1 and an INterface Circuit INC1 for the S interface. The second telecommunications interface DIPS contains a Radio Portable Part RPP, an InterWorking Unit IWU2 and an INterface Circuit INC2 for the S interface. The radio fixed part RFP and the radio portable part RPP in this case form the known DECT/GAP system DGS.
The following general problems arise for a DECT-specific RLL system as a carrier for, as far as possible, all ISDN services in the subscriber connection:
Simulation of the D Channel
Characteristics of the D Channel
Dect Channels
Based on the document "Nachrichtentechnik Elektronik" (Telecommunications electronics) 42 (1992) January/February, No. 1, Berlin, DE; U. Pilger; "Struktur des DECT-Standards (Structure of the DECT standard)", pages 23 to 29, in conjunction with ETS 300 175-1 . . . 9, October 1992", FIG. 2 shows the TDMA structure of the DECT/GAP system DGS. The DECT/GAP system is a hybrid system with respect to the multiple access methods, in which radio messages can be transmitted, using the FDMA principle, on ten frequencies in the frequency band between 1.88 and 1.90 GHz and, using the TDMA principle according to FIG. 2, can be transmitted in a predetermined time sequence from the base station RFP to the portable part RPP and from the portable part RPP to the base station RFP (duplex operation). The time sequence is in this case governed by a multiple time frame MZR, which occurs every 160 ms and has 16 time frames ZR, each having a time duration of 10 ms. Information items are transmitted separately in these time frames ZR to the base station RFP and the portable part RPP, these information items relating to a C-, M-, N-, P-, Q-channel defined in the DECT standard. If information items for a number of these channels are transmitted in one time frame ZR, then the transmission is carried out on the basis of a priority list where M&gt;C&gt;N and P&gt;N. Each of the 16 time frames ZR in the multiple time frame MZR is in turn split into 24 time slots ZS each having a time duration of 417 .mu.s, of which 12 time slots ZS (time slots 0 . . . 11) are intended for the transmission direction "base station RFP.fwdarw.portable part RPP", and a further 12 time slots ZS (time slots 12 . . . 23) for the transmission direction "portable part RPP.fwdarw.base station RFP". In accordance with the DECT standard, information items with a bit length of 480 bits are transmitted in each of these time slots. Of these 480 bits, 32 bits are transmitted as synchronization information in a sync field, and 388 bits as useful information in a D field. The remaining 60 bits are transmitted as additional information in a Z field and as protection information in a "guard time" field. The 388 bits in the D field which are transmitted as useful information are in turn split into a 64-bit long A field, a 320-bit long B field and a 4-bit long "X-CRC" word. The 64-bit A field is composed of an 8-bit long data header, a 40-bit long data set with data for the C-, Q-, M-, N-, P-channels and a 16-bit long "A-CRC" word.
Characteristics
The DECT standard also offers other channel structures, for example a C.sub.f channel (f=fast).
On the basis of the OSI/ISO layer model (cf. (1): Information sheets--Deutsche Telekom Year 48, February 1995, pages 102 to 111; (2): ETSI publication ETS 300175-1 . . . 9, October 1992; (3): ETSI publication ETS 300102, February 1992; (4): ETSI publication ETS 300125, September 1991; (5): ETSI publication ETS 300012, April 1992), FIG. 3 shows a model of the C plane in the "ISDN.revreaction.DECT specific RLL/WLL" telecommunications system IDRW-TS according to FIG. 1.
On the basis of the OSI/ISO layer model (cf. (1): Information sheets--Deutsche Telekom Year 48, February 1995, pages 102 to 111; (2): ETSI publication ETS 300175-1 . . . 9, October 1992; (3): ETSI publication ETS 300102, February 1992; (4): ETSI publication ETS 300125, September 1991; (5): ETSI publication ETS 300012, April 1992), FIG. 4 shows a model of the U plane for voice data transmission in the "ISDN.revreaction.DECT specific RLL/WLL" telecommunications system IDRW-TS according to FIG. 1.
Bandwidth Economy
The C.sub.s channel structure offers optimum bandwidth economy for a standard voice link, since only one transmission path (bearer)--for example MBC to the LCNy, LCN1 according to FIG. 5--one link or one time slot is required according to FIG. 5 and on the basis of FIGS. 3 and 4, and taking account of the ETSI publications (ETS 300175-1, October 1992, Chapter 7; ETS 300175-3, October 1992, Chapter 4.1; ETS 300175-4, October 1992, Chapter 4).
According to FIG. 5 and on the basis of FIGS. 3 and 4 and taking account of the ETSI publications (ETS 300175-1, October 1992, Chapter 7; ETS 300175-3, October 1992, Chapter 4.1; ETS 300175-4, October 1992 Chapter 4), the use of the C.sub.f channel leads to reduced bandwidth economy, since the U plane itself requires a further transmission path (bearer), a further link or a further time slot; that is to say two transmission paths (bearers) are required--for example MBC to the LCN2, LCNz and MBC to the LCNy, LCN1 according to FIG. 5--two links or two time slots are required for a single voice link.
Furthermore, three transmission paths (bearers)--for example MBC to the LCNx, LCN0, MBC to the LCNy, LCN1 AND MBC to the LCNz, LCN2 according to FIG. 5--three links or three time slots are required for the case when there are two ISDN-B channel links (voice links).
While the use of the C.sub.f channel appears to be expedient from the viewpoint of channel capacity, the use of the C.sub.s channel is expedient from the point of view of bandwidth economy.